This invention, relates to a multiple spectral imager which utilizes a two-dimensional detector array to register spectral information in a first direction and spatial information in a second direction.
Multiple spectral imagers have been used in a variety of aircraft and spacecraft remote sensing imaging applications. Previously reported designs for such imagers include the designs known by the acronyms NIMS, VIMS, AVIRIS, SISEX, AIS and TIMS. These previous designs suffer from a variety of drawbacks, varying with the particular design. For example, several of these designs include a central obscuration, a relatively complex implementation or a difficult detector interface. In general, a central obscuration adds complexity to the configuration, reduces light collecting area, adds stray light, and adversely affects diffraction. The SISEX system utilizes a single collimator and a single spectrometer primary mirror to provide light to both short wave infrared (SWIR) and visible/near infrared (VNIR) spectrometers. This approach brings with it the need for a dichroic beam splitter to separate the SWIR and the VNIR optical paths.
The present invention is directed to a spectral imager which in the preferred embodiments described below eliminates the need for such dichroic beam splitters, and which takes a new approach to the optical layout for such an imager.